<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        let str1 = 'hello word';
        // 多余的变量值是undefined，k对应undefined
        let [a,b,c,d,e,f,g,h,i,j,k] = str1; // 当做数组处理
        console.log(a,b,c,d,e,f,g,h,i,j,k);
        let {
            length: len,
            toLocaleUpperCase: fn1
        } = str1;
        console.log(len);
        console.log(fn1.call(str1));
        let str2 = 'aa';
        // str2.up()
    </script>
</body>
</html>